New Single-Phase, White-Light-Emitting Phosphors Based on δ-Gd2Si2O7 for Solid-State Lighting

Two new white-light (WL)-emitting phosphors (δ-Gd 2 Si 2 O 7:Dy and δ-Gd 2 Si 2 O 7:Eu,Tb) have been synthesized by the sol–gel method. The Gd-Ln 3+ (Ln 3+ = Dy 3+, Tb 3+, Eu 3+ ) energy-transfer band has been used to excite both phosphors, which provides an enhancement of the Ln 3+ emissions. First, WL was generated from δ-Gd 2 Si 2 O 7: x Dy thanks to the particular ratio of the blue and yellow emissions observed in all three compositions, which had chromatic coordinates of x = 0.30, y = 0.33 and CCT values of between 7077 and 6721 K. The decay curves of the main transitions of Dy 3+ showed a maximum lifetime value for δ-Gd 2 Si 2 O 7:0.5%Dy, which is, therefore, the most efficient doping level. Second, a broad spectral range, single-phase, WL-emitting phosphor was generated by codoping δ-Gd 2 Si 2 O 7 with Tb 3+ and Eu 3+ . The composition δ-Gd 2 Si 2 O 7:0.3%Eu 3+;0.8%Tb 3+ showed CIE coordinates well inside the ideal WL region of the CIE diagram and a CCT value of 5828 K. The single-phase WL-emitting phosphors presented in this paper are promising materials to be used in white solid-state lighting systems and field-emission displays due to the advantages provided both by Gd 3+ ions and by the high thermal and chemical stabilities of the rare earth disilicate matrix.